Centers for Disease Control and Prevention

Clinical considerations for RSVpreF maternal vaccine 

and nirsevimab

Jefferson Jones MD MPH FAAP

CDR USPHS

Co-Lead, Respiratory Syncytial Virus Vaccines - Pediatric/Maternal 

Work Group

Coronavirus and Other Respiratory Viruses Division

National Center for Immunization and Respiratory Diseases

June 22, 2023
2

Policy questions for ACIP vote

▪ Should vaccination with Pfizer RSVPreF vaccine (120μg antigen, 1 dose IM given 24-

36 weeks gestation) be recommended for pregnant people to prevent RSV disease 

in infants?

▪ Should one dose of nirsevimab be recommended for infants born during or 

entering their first RSV season and <8 months of age at time of immunization?

▪ Should one dose of nirsevimab be recommended for children who are at increased 

risk of severe RSV disease entering their second RSV season and <20 months of age 

at time of immunization?
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Potential advantages of maternal vaccination versus a 

monoclonal antibody (mAb)

▪ A maternal vaccine may be lower in price 

▪ A mAb is not a traditional vaccine and many issues may complicate implementation

– Insurance coverage, vaccine schedule, immunization registries, safety monitoring

▪ Maternal vaccine provides protection from birth, when infants are at highest risk

– A mAb must be timed correctly to provide protection during the RSV season, and atypical RSV 

transmission may lead to unprotected infants

▪ Maternal vaccine induces a polyclonal antibody response, which should be more resilient to 

mutations than a monoclonal antibody

– Evidence suggests that mutations resulting in nirsevimab resistance are rare, but naturally 

occurring resistant mutations have been detected1,2

– Mutations resulted in poor efficacy of a previous mAb product (suptavumab)

3

1 Abram IDweek 2022. 2 Abram 12th RSV International Symposium 2022. 3 Simões CID 2021. 
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Potential advantages of mAb over maternal 

vaccination

▪ Imbalance for preterm birth observed after RSVpreF vaccine vs. placebo in maternal clinical 

trials, but not statistically significant1

▪ No head-to-head trials comparing efficacy, but protection from maternal vaccination likely 

wanes more quickly1–4

▪ Estimated half-life in nirsevimab trials

– Nirsevimab: 63–73 days

5,6

– Infection-induced maternal RSV antibodies: 36–38 days5

▪ Nirsevimab administration can be timed to be given when infant is entering RSV season

1 Kampmann NEJM 2023. 2 Muller NEJM 2023. 3 Madhi NEJM 2020. 4 Nunes F1000Res 2018. 5 Wilkins Nat Med 2023. 6 Griffin NEJM 2020.
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Potential advantages of mAb over maternal 

vaccination (continued)

▪ Protection from maternal vaccination relies on sufficient transplacental transfer of 

antibodies, which may be reduced in

– Infants born soon after maternal immunization1

– Infants born premature2

– Maternal disease2

▪ Maternal uptake of flu and Tdap vaccines lower than routine childhood vaccines3,4 

– Unclear if pregnant people willing to accept multiple vaccines during pregnancy

– However, flu vaccine uptake among children only mildly higher than among pregnant 

people

– Uptake of maternal RSVpreF vaccine and nirsevimab unknown

1 https://www.cdc.gov/vaccines/pregnancy/vacc-during-after.html. 2 Palmerira Clin Dev Immunol 2012. 

3https://www.cdc.gov/flu/fluvaxview/pregnant-women-apr2022.htm. 4 Hill MMWR 2023
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Benefits of both products being available

▪ Each product has certain advantages

▪ Parental preferences may differ, as suggested by survey asking pregnant people 

about product preference if both available1

– 28% only maternal vaccine

– 25% only RSV antibody injection

– 38% both

▪ Some populations lack access or do not present for prenatal care, precluding 

maternal vaccination

▪ Scenarios may exist for which use of both products may be warranted to maximize 

protection from RSV-associated severe disease

– 8% none

– 1% other

1 Unpublished CDC and University of Iowa/RAND survey of 523 people currently pregnant or pregnant within last 12 

months of survey conducted December 21, 2022-January 2, 2023
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Cost effectiveness summary

▪ Cost effectiveness of giving nirsevimab if mother had been vaccinated

– $668,735/QALY if given to all infants

– $486,882/QALY if given to infants born April to September

▪ Cost effectiveness of giving RSVpreF to mother if nirsevimab will be 

given

– More than $10,000,000/QALY on average
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Challenges if nirsevimab recommendations relate to 

maternal vaccination status

▪ Maternal vaccination status might be unknown

▪ Transferring documentation of maternal vaccination to the healthcare 

provider of infant may be difficult

– Limited information available during birth hospitalization

– Less information regarding receipt of prenatal vaccinations may be 

available to infant primary care providers
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Draft clinical considerations if both RSVpreF and 

nirsevimab are licensed and recommended

▪ Either maternal vaccination with RSVpreF or nirsevimab is recommended to 

prevent RSV disease, but both products are not needed for most infants

▪ Risks and benefits of both RSVpreF and nirsevimab should be considered 

when deciding on maternal vaccination

▪ If mother vaccinated, nirsevimab can be considered if infant considered to 

have insufficient protection from vaccine or is at high risk of severe disease
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Scenarios to consider administration of nirsevimab

when mother has been vaccinated

▪ Receipt of maternal vaccine not confirmed by healthcare record

▪ Infant born within 14 days of vaccination

▪ Infant born premature

▪ Healthcare provider recommends maximizing protection because infant at 

high risk of severe disease

– Especially important if born >3 months prior to peak of RSV season
For more information, contact CDC

1-800-CDC-INFO (232-4636)

TTY: 1-888-232-6348 www.cdc.gov

The findings and conclusions in this report are those of the authors and do not necessarily represent the 

official position of the Centers for Disease Control and Prevention.